For a foreign citizen to become become a U.S. citizen.
The mediate cause for World War 1 the assassination of Archduke Franz Ferdinand and his pregnant wife Sophie. However there were many other causes of WW1. WW2 started because hitler didn’t like Jewish people so he built an army to destroy all Jewish people wich then started the war.

Manchuria rich in natural resources and sparsely populated had obvious advantages for a densely populated and resource-poor Japan. Amongst Manchuria's resources coveted by Japan were iron, coking coal, soybeans, salt and above all land, all severely lacking within the Japanese empire in 1930.
The two groups that fought each other in World War I became known as the Triple Alliance (the main forces were Germany, Austria-Hungary, the Ottoman Empire and Italy) and the Triple Entente (the main forces were Russia, Great Britain and France)
In 1860, Lincoln won the party’s presidential nomination. In the November 1860 election, Lincoln again faced Douglas, who represented the Northern faction of a heavily divided Democratic Party, as well as Breckinridge and Bell.